The figure inside had witnessed what happened (9)

I believe the answer is:

seventeen

I'm a little stuck... Click here to teach me more about this clue!

'the figure' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for seventeen that I've seen before include "next clue" , "Cardinal number" , "odd number" , "Quite a few" , "XVII" .)

I've seen this clue in the Evening Standard.

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